594 research outputs found
Bioenergetics of early life-history stages of the brachyuran crab Cancer setosus in response to changes in temperature
No full textIn many marine invertebrates, a latitudinal cline in egg size is considered an adaptive response to a decrease in temperature, and enhances the energetic fitness of their larvae at hatching. However, the amount of energy carried over from the egg to the larval stage depends on the metabolic efficiency of egg development. In the present study, eggs of the brachyuran crab Cancer setosus were sampled for their dry mass (DM), carbon (C), nitrogen (N), and fatty acid (FA) content throughout development from blastula stage until hatching of zoea 1-larvae at Antofagasta (23°S) and Puerto Montt 41°S (Chile) under different temperature treatments (12, 16 and 19 °C). Hatching zoea 1 larvae contained 60 ± 3% of the initial blastula egg C content, regardless of site or temperature. However, the ontogenetic decrease in egg C content was to a significantly higher extend based on the utilization of energy-rich FA at 12 °C (? 1.16 µg/egg) compared to the 19 °C treatments in Antofagasta and Puerto Montt (? 0.63 to ? 0.73 µg FA per egg). At 19 °C egg-metabolism was based to a substantial extend on protein, which allowed for the saving of energy-richer lipids. We conclude that the production of larger eggs with high FA content appears to be adaptive not only to fuel the larval development, but is also a response to the prolonged egg developmental times at lower temperatures.<br/
Triterpenols in mangrove sediments as a proxy for organic matter derived from the red mangrove (Rhizophora mangle)
No full textMangroves are the dominant type of vegetation along many tropical coasts. Organic matter (OM) derived from mangrove leaf litter and root material is stored in sediments and is a major contributor to the amount and chemical composition of sedimentary OM. A set of organic biomarkers in sediments was applied as a palaeo-indicator for the Holocene dynamics of a mangrove Estuary (Rio Caeté, Pará, Brazil). Six sediment cores were collected perpendicular to the present coast line and analysed for triterpenols and sitosterol. The influence of microbial biomarker degradation was implemented from a previous study. Biomarker profiles were validated with pollen data and multivariate statistics to test whether these compounds were suitable indicators for the palaeo-vegetation. Sediments deposited up to 2 Ma BP showed biomarker assemblages similar to those of recent surface sediment. In two cores, the biomarker composition revealed a transition from marsh to mangrove vegetation. Taraxerol, germanicol and b-amyrin provided the most significant chemotaxonomical information and, especially in combination, served as reliable proxies for OM from Rhizophora mangle in northern Brazil. The maximum age of the mangrove system ranged between 1000 and 5100 yr depending on the topographic elevation of the drilling location.Fil: Koch, Boris Peter. Alfred Wegener Institute for Polar and Marine Research; Alemania. University of Applied Sciences; AlemaniaFil: Souza Filho, Pedro. Federal University of Pará; BrasilFil: Behling, Hermann. University of Göttingen; AlemaniaFil: Cohen, Marcelo C. L.. University of Pará; BrasilFil: Kattner, Gerhard. Alfred Wegener Institute for Polar and Marine Research; AlemaniaFil: Rullkötter, Jürgen. Carl von Ossietzky University of Oldenburg; AlemaniaFil: Scholz Böttcher, Barbara. Carl von Ossietzky University of Oldenburg; AlemaniaFil: Lara, Ruben Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Center for Tropical Marine Ecology; Alemani
Lipid, fatty acid and protein utilization during lecithotrophic larval development of Lithodes santolla (Molina) and Paralomis granulosa (Jacquinot)
No full textDuring the larval development of the subantarctic king crab, Lithodes santolla, and stone crab, Paralomis granulosa, we compared changes in the carbon, fatty acid and protein contents of larvae reared under constant conditions from hatching to metamorphosis, either in presence or absence of food (Artemia spp. nauplii). In both species the feeding condition had no influence on any of the chemical parameters studied, indicating a fully lecithotrophic (i.e. non-feeding) mode of development from hatching of the first zoea to metamorphosis of the late megalopa. Dry mass and carbon contents at hatching were similar in the larvae of both species, but L. santolla contained initially higher total amounts of fatty acids and protein than P. granulosa. Both species utilized considerable portions of their total fatty acid pool which decreased logarithmically throughout the time of development. At metamorphosis, it was almost exhausted in P. granulosa, while L. santolla had consumed only about 60%. Protein utilization, in contrast, was higher in L. santolla (40%) than in P. granulosa (20%). Triacylglycerol was the principal storage lipid in both species, accounting initially for about 75% of the lipid fraction; it was strongly utilized during larval development. Phospholipid constituted the second largest lipid class; it also decreased in P. granulosa, but to a lesser extent in L. santolla. The major fatty acids of both species were 18:1(n?9), 20:5(n?3) and 16:0 as well as, in lower proportions, 18:1(n?7), 22:6(n?3), 16:1(n?7) and 18:0. Monounsaturated fatty acids represented the dominant group in L. santolla, whereas P. granulosa contained similar amounts of mono- and polyunsaturated fatty acids. In L. santolla, monounsaturated fatty acids, especially 16:1(n?7), were preferentially utilized as compared to polyunsaturates. Due to a particularly strong lipid utilization in P. granulosa, all individual fatty acids were largely depleted at metamorphosis, showing similar extents of consumption. L. santolla had higher initial lipid and protein stores that seem to be used more economically as compared to P. granulosa. <br/
(Table 1) Temperature, salinity and dissolved organic carbon during POLARSTERN cruise ARK-XIII/3
No full text(Table 1) Temperature, salinity and dissolved organic carbon during POLARSTERN cruise ARK-XIII/
(Table 2) Composition and concentration of total hydrolyzable neutral sugars in samples taken during POLARSTERN cruise ARK-XIII/3
No full text(Table 2) Composition and concentration of total hydrolyzable neutral sugars in samples taken during POLARSTERN cruise ARK-XIII/
Inorganic nutrients measured on water bottle samples during POLARSTERN cruise ARK-XXIII/2
No full textFluxes of nutrients in a three-dimensional meander structure of the Antarctic Polar Front
No full textThe horizontal and vertical advection and the vertical diffusion of two plant nutrients (nitrate and silicate) are estimated at the Antarctic Polar Front (APF) in the Atlantic sector using quasi-synoptic, high-resolution physical and chemical measurements. Our results suggest that the routes of nutrient supply are more complex than indicated by existing large-scale views. The vertical advection associated with mesoscale upwelling events is shown to be between two and three orders of magnitude larger than the diffusion, and to potentially amount to the phytoplankton uptake rate locally. Averaged over the survey area, however, the vertical nutrient transport is downward and concords with the front acting as a barrier to the northward export of surface nutrients by the Ekman drift. This poses significant constraints on the global cycles of nutrients and may have an impact in the sediment record
Continuous thermosalinograph oceanography along POLARSTERN cruise track ANT-XX/1
No full textVersion 2, 2016-10-2
Continuous thermosalinograph oceanography along POLARSTERN cruise track ANT-XXVIII/2
No full textVersion 2, 2016-10-2
Fatty acid composition of wild Odontesthes bonariensis (Valenciennes 1835) larvae: implications on lipid metabolism and trophic relationships
No full textThe fatty acid composition of the pejerrey Odontesthes bonariensis larvae was studied to elucidate potential dietary relationships. Their principal fatty acids were characteristic for membrane lipids of aquatic organisms. The fatty acid composition varied little throughout seasons, with high proportions of 22 : 6(n-3) (27% of total fatty acids), which is biosynthesized de novo from dietary precursor fatty acids and/or accumulated from the diet. Other major fatty acids were 16 : 0 and 18 : 0. The diatom-typical 16 : 1(n-7) and other dietary fatty acids (zooplankton and microplankton) are not reflected in the larvae, thus limiting the use of fatty acids as trophic markers for food web relationships of atherinopsids.Fil: Kopprio, Germán Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Graeve, Martín. Alfred Wegener Institute Helmholtz Center for Polar and Marine Research; AlemaniaFil: Kattner, Gerhard. Leibniz Center for Tropical Marine Ecology; AlemaniaFil: Lara, Ruben Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Leibniz Center for Tropical Marine Ecology; Alemani
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